Catheter-based cardiac procedures such as cardiac ablation may sometimes cause damage to the esophagus, since sections of the esophagus often pass in close proximity to the left atrium and coronary sinus. The anatomical proximity of the left atrium to the esophagus is described, for example, by Lemola et al., in “Computed Tomographic Analysis of the Anatomy of the Left Atrium and the Esophagus: Implications for Left Atrial Catheter Ablation,” Circulation, (110:24), Dec. 14, 2004, pages 3655-60, which is incorporated herein by reference. The proximity of the coronary sinus to the esophagus is described, for example, by Tsao et al., in “Anatomic Proximity of the Esophagus to the Coronary Sinus: Implication for Catheter Ablation Within the Coronary Sinus,” to be published in the Journal of Cardiovascular Electrophysiology, (17:4), Apr., 2006, which is incorporated herein by reference.
Some methods and systems are known in the art for enhancing the safety of such procedures. For example, Pollak et al., describe imaging techniques for imaging the esophagus in a report entitled “Novel Imaging Techniques of the Esophagus Enhancing Safety of Left Atrial Ablation,” Journal of Cardiovascular Electrophysiology, (16:3), March, 2005, pages 244-248, which is incorporated herein by reference.
The report describes imaging techniques performed during radio-frequency (RF) catheter ablation of atrial fibrillation in the left atrium. According to the report, a mixture of barium cream and gadolinium diglutamate allowed esophageal imaging during magnetic resonance angiography of the left atrium and pulmonary veins. In another technique, barium cream used during computer tomography angiographic imaging of the left atrium and pulmonary veins allowed esophageal imaging. The esophagus was also imaged with an electroanatomic mapping system. According to the report, esophageal and left atrial imaging helped to avoid catheter ablation in left atrial tissue overlapping the esophagus.
Wu and Wang describe a method of using left atrial esophagus imaging for a balloon valvuloplasty application in a report entitled “Using Left Atrial Esophagus Impression After a Barium Swallow to Determine the Optimal Septal Puncture Site During Percutaneous Balloon Mitral Valvuloplasty,” Canadian Journal of Cardiology, (19:13), December, 2003, pages 1509-1512, which is incorporated herein by reference. The study describes methods for transseptal catheterization for percutaneous balloon mitral valvuloplasty (PBMV) procedures. The left atrial (LA) impression on the esophagus after a barium swallow was used as a reference of LA silhouette to determine the septal puncture site.